Biochemistry: Vitamin D & the Races of Man

The very existence of the essential
vitamin D, or "sunshine vitamin," was not established until the present
century, but its imprint upon history goes back a million years or
more. According to a theory now elaborated by Brandeis University
Biochemist W. Farnsworth Loomis, it is because of the human body's
need to take in a certain amount of vitamin D, but not too much, that
the human species has developed into three principal racial groups
distinguished by skin color and loosely called black, yellow and white.